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Pin Functions:
Table 1-4 gives a concise description of the function of each pin.
Table 1-4 Pin Functions
Pin No.
CP-84, FP-80A,
CG-84
16, 55
Type
Power
Symbol
V
CC
TFP-80C
5, 42
I/O
I
Name and Function
Power:
Connected to the power supply (+5 V).
Connect both V
CC
pins to the system power
supply (+5 V). The chip will not operate if either
pin is left unconnected.
Ground:
Connected to ground (0 V).
Connect all V
SS
pins to the system power
supply (0 V). The chip will not operate if any V
SS
pin is left unconnected.
Crystal:
Connected to a crystal oscillator.
The crystal frequency should be double the desired
clock frequency.
If an external clock is input at the EXTAL pin, leave
the XTAL pin unconnected.
External Crystal:
Connected to a crystal
oscillator or external clock. The frequency of the
external clock should be double the desired clock
frequency. See section 8.2, “Oscillator Circuit” for
examples of connections to a crystal and external
clock.
System Clock:
Supplies the clock to peripheral
devices.
Enable Clock:
Supplies an E clock to E clock
based peripheral devices.
Bus Request Acknowledge:
Indicates
that the bus right has been granted to an external
device. Notifies an external device that issued a
BREQ signal that it now has control of the bus.
V
SS
2, 24
41, 42
64, 83
12, 29
71
I
Clock
XTAL
1
70
I
EXTAL
84
69
I
3
72
O
E
4
73
O
System
control
BACK
5
74
O
17